The invention concerns an improved process for the preparation of macrocyclic products with 12 or more ring atoms containing one or more polar functional groups on the ring and/or one or more heteroatoms within the ring by ring closing metathesis (RCM) of suitably substituted diene precursors, which more specifically can be applied to the synthesis of olfactory compounds, perfumary ingredients, pheromones, crown ethers, antibiotics and pharmaceuticals for human and veterinary medicine.